A low-dose scanning-beam digital x-ray (SBDX) fluoroscopy system is being developed. The expected patient exposure is 10% of conventional fluoroscopy with comparable image quality. The low-dose capability is achieved by virtually eliminating scattered radiation detection, elimination of the anti-scatter grid, improved detector efficiency, and a larger patient entrance aperture. A prototype SBDX system, designed for cardiac fluoroscopy, is nearing completion. Interventional neuroradiology would also benefit greatly from a decrease in exposure. However, the neuroradiological application will require an increase in SBDX spatial resolution. This proposal seeks to redesign the prototype SBDX system for neuroradiology and test the performance of the redesigned system. The specific aims of this proposal are; i) measure the modulation transfer function of the prototype SBDX, ii) modify the prototype to increase spatial resolution, iii) measure the increase in vessel contrast in the scatter-free SBDX image, in a neuroradiological setting, and iv) measure the decrease in patient exposure resulting from SBDX in a neuroradiological setting. The ICRP has recommended and the FDA has adopted a system of dose limitation for patients based on justification and ALARA (as low as reasonably achievable). The successful completion of this research would allow the construction of a neuroradiology x-ray system with previously unachieved levels of safety. PROPOSED COMMERCIAL APPLICATION: Current neuroradiological imaging systems used in diagnostic and therapeutic procedures expose the patient and the physician to an unhealthy dose of x-rays. The installed base of such systems is expected to grow rapidly in the U.S. If a system with substantially lower exposure and comparable price and performance were available, the market for that system would be substantial.